Typically a mobile radio device or a smartphone, is operated via a touchscreen, which encompasses the touch-sensitive input surface. Random, inadvertent contact with the touchscreen, e.g., when handling the portable/mobile device, could lead to incorrect operation. Thus, an operator could pick up the unlocked device, e.g., a smartphone, to put it in a pocket, and in doing so unintentionally select an entry in a call list and make a call using the device.
Furthermore, for many operations like inputting the correct code, e.g., a PIN or a pattern, to unlock the device, the operator has to touch a comparably small operating area. Along with increased concentration on the part of the operator, i.e., the user, this also requires a certain period of time. A similar problem arises when rejecting an incoming call or quickly muting the device's microphone in certain situations like when the operator is on a call.